Helsinki’s clayey soil has been thoroughly surveyed

“It is our job to build Helsinki,” say engineer Helena Färkkilä-Korjus and acting head of geotechnical engineering Markku Savolainen about their work. Färkkilä-Korjus studies the geotechnics of land use plans in the Technical and Economic Office of the Helsinki City Planning Department. Savolainen participates in construction projects in the Geotechnical Division of the Real Estate Department.

The common denominator between their jobs is soil. “When we start to plan construction work, it is good to know what kind of ground we are building,

Land use planning requires that we are aware of a wide range of other factors that affect construction work, such as traffic and wind. In addition, security factors have to be taken into account in land use planning, for example in the vicinity of power plants,” Färkkilä-Korjus explains.

Careful investigation in advance saves costs in later stages of the project. Although Färkkilä-Korjus’ office, where 12 experts work, is the only one in Finland, she thinks that the technical and economic aspects will become more important everywhere as resources become scarcer.

“We already have quite a lot of information about the soil in Helsinki region,” Savolainen says.

“If we need information about the areas of Helsinki that are located outside the city limits, we use GTK’s maps,” Savolainen adds.

Malmi is a good area for building

A significant part of the Helsinki region is clayey soil. Clay became a topic of public discussion after the plans to transform the Malmi airport area to a residential area were published. According to Savolainen, the area is good for construction work according to Helsinki standards, because it does not contain man-made filling materials.

“From the point of view of geotechnics, the biggest challenge related to soil is the actions of humans – mostly unplanned land filling and contaminated soil. Poorly planned land filling may cause significant challenges to foundation work and increase the costs of construction,” Savolainen says.

In order to support careful planning, the City Planning Department ordered an investigation of the history of the region’s argillaceous deposits from GTK.

“After we have investigated the geological history of the argillaceous deposits and their types, it is easier to target further surveys,” Färkkilä-Korjus explains.

In addition to the Malmi district, the geotechnical experts of Helsinki are currently kept busy, for example, in Kalasatama, Hernesaari, Jätkäsaari, Kruunuvuori, Vartiosaari, and Östersundom.